Quote Originally Posted by Silverpixels5
My 180 works fine with my 500C/M. Although I believe a very slight portion of the top of the image gets cut off in the viewfinder. That part is in the negative though. I could be wrong though....it may be that that part gets obstructed from the viewfinder when I have the extension tube on with the 180.
It`s a well known flaw of the 500`s C-C/M, vignetting with lenses longer than 150mm, that`s why they built a bigger mirror for the 501 C/M.